Śatapatha Brāhmaṇa ("of a hundred paths") 11.5.2.3

11.5.2.3

ayameva dakṣiṇa ūrurvaruṇapraghāsāḥ tasya yāni pañca havīṃṣi samāyīni tā imāḥ pañcāṅgulayaḥ kulphāvevaindrāgnaṃ havistadvai dvidevatyam bhavati tasmādimau dvau kulphāvidaṃ vāruṇamidam mārutamanūkaṃ kāyastadvā aniruktam bhavati tasmāttadaniruktam

The Varunapraghâsa offerings are this right leg,--the five oblations which this has in common (with the other Seasonal offerings) are these five toes; and the oblation to Indra and Agni is the knuckles: this (oblation) belongs to two deities whence there are these two knuckles. That (oblation) to Varuna is this (shank); that to the Maruts this (thigh); and that (cake) to Ka is this back-bone: this (oblation) is indistinct, whence that (back-bone) is indistinct.